Fluid-operated press



Patented Dec. 7, 1943 UNITED STATES PATENT e mc t;

' 2,335,917 I v FLUID-OPERATEI! raEss land, assignor' to Broom and WadeLimited, High Wycombe, England, a British company Application May 27,1942,"Serial No. 444,724

In Great Britain June 5, 1941 18 Claims. -(Cl'. 60- 97) This inventionrelates to power presses for performing any desired particular operationsuch for example as riveting, punching, shearing, actual pressing orotherwise, of the type in'which the press includes a power pistonworking in a power cylinder to actuate a piston rod or ram whichtransmits the actual force to perform the necessary work, the pressbeing operated by a liquid under a high working pressure (such assupplied from an intensifier), and has for its main object to providesuch devices of an extremely efiicient and simple form.

As is well known, in the majority of presses it is not necessary for thepower piston and its rod,

ram or the like to transmit a high working force throughout the whole ofits stroke, but it is sufiioient if the maximum force is exerted for adesired proportion of the stroke at its conclusion; in other words, thetotal stroke can be divided into what may be termed the approach portion(requiring but slight force) and the working portion (requiring the fullforce).

The present invention has for its object to provide means by which thepower piston and parts connected therewith can be movedfor the approachportion of the stroke without the pres sure liquid acting upon the powerpiston for the purpose, the said pressure liquid then acting upon thepower piston to carry out'the working portion of the stroke.

In general, presses in accordance with the invention are provided withasubsidiary cylinder of smaller diameter than the power cylinder inwhich works a subsidiary piston directly or indirectly connected withthe power piston and its rod, ram or the like, the arrangement beingsuch that the approach portion of the stroke is effected by the pressureliquid acting upon the subsidiary piston to move it and the powerpiston, and the construction including automatically operated valvemeans whereby when the approach portion of the stroke is eiiectedthepressure liquid is caused to act upon the working face of the powerpiston for the performance of the "working portion of the stroke.

The automatically operated valve means can have various constructionsand be operatedin accordance therewith. In most forms, however.

stroke terminates then the continuedpressure' of the pressure liquid onthe subsidiary piston causes the parts to move to the other extremeposition and by this slight movement, a suitable partor parts effect theopening of a valveto allow the pressure liquid to pass to the powercylinder'and operate upon the working face of the'power piston. When theworkng portion of the stroke has been effected, upon the return'ofthe-parts this spring acts to bring the parts oi the connection intotheir original position. i I Preferably the construction is such-thatthepower cylinder is filled on both sides of the power piston with theworking liquid, a passage oripase sages being provided through thepower'piston or from end to end of the power' cyli'nderto enable thesaid liquid to pass from side to side'iof the power piston during theapproach portion of the stroke, but having means combined therein anautomatic manner by the same .mean'sras way of example only and inwhichthat which opens the valve for supplying .thezliq uid underpressure to act uponthe power piston;

Additionally. and by preference, a reservoir or compensating chamber mayalso be providedfor the working liquid in connection-with thexpowercylinder. This suitably communicates with-the power cylinder. and bypreference on the side-re mote from that in which the working face ofthe power piston forms a boundary.

, As will be realised, many constructions may be adopted for carryingthe invention into effect and presses in accordance with theinvention'may be fixed or portable, in any case, especiallythe 1attercase, if desired the intensifier being separate from the-press proper. 1

In order that the invention may be better understood it will now bedescribed with reference to the accompanying drawing, which isgivenbyFig. 1 shows in elevation one structural meth: od of carrying theinvention into efiectjpartlytin section with the power piston at the-upper {end of its stroke.

Fig. 2 shows a fragmentary portion of 1, but with the power piston in.the.position," iust after the commencement of the power stroke and someparts shown in modified form. 1' I.

"In the drawing, 3 is the power cylinder hav-v ingone integral closedend 4 which is apertured respondingly threaded bore of one arm of a yokel I of any usual construction, the parts being held in position by alocknut l2. The other arm of the yoke carries one of the dies or thelike I3, the other die [4 being carried on the end of the piston rod 9.

The cylinder 3 has an exterior jacket Hi thereon which abuts a flange Itat one end with the interposition of suitable packing. The other end Hextends beyond the end 4 of the cylinder 3 and abuts a clamping plateill with the interposition of packing forming the exterior flange ofanairfilled rubber cushion it of hollow annular V- shaped section.

A thrust sleeve is also comes around a portion of the subsidiarycylinder 5 to abut at one of its ends with suitable packing the end 4 ofthe cylinder 3, and at the other end the interior flange of the cushionIS.

The plate I! is apertured and held on the cylinder 5 by a nut inscrew-threaded engagement with a screw-threaded portion on the end ofthe cylinder 5 which projects through the said plate [1.

By the shape and construction of the parts a space 2| is left betweenthe exterior of the cushion IS, a portion of the interior of the jacketl5 and the outer surface of the end 4, which space constitutes a liquidreservoir. The exterior of the cylinder 3 has between itself and theinterior surface of the jacket l5 a number of passageways 22 whichcommunicate on the one hand by conduits 23 with the space 2| and on theother hand through apertures 24 with the interior of the cylinder 3.

25 is the power piston working in the cylinder 3, which is not connecteddirectly to the piston rod 9 but through the following mechanism.'Secured to its rear is a sleeve 26 by means of a flange, this sleeve onthe interior having two diameters. The larger diameter is in the portionadjacent the piston 25 and is a close sliding fit on an enlarged portion21 on the end of the piston rod 9. The smaller diametered portion is inthe nature of a flange 28 the interior diameter of which is a closesliding fit on the piston rod e, the step between the two diameters ofthe piston rod forming a limiting abutment for the flange 28. Theenlarged portion 21 has a recess 21 therein and between this recess andanother recess 29 at the rear of the piston 25 is located a compressionspring 3%) of suitable strength. The arrangement is such that normallythere is a certain distance between the actual end 3| of the enlargedportion 2'! and the actual surface 32 at the rear of the piston 25. Incertain conditions, however, these surfacescome into contact. When heldseparate by the spring action 35, the space between the surfaces 3i and32 communicates with the interior of the cylinder 3 below the piston 25,by means of apertures 33 in the sleeve 26. The arrangement between theparts, however, is such that theseapertures are closed by the exteriorsurface of the enlargement 2! when the piston 25 contacts by its surface32 with the surface iii of the enlargement 27 (Fig. 2)

The subsidiary cylinder 5 has working therein a subsidiary piston 3%which is formed hollow and at its front has a stepped flange 35 securedby suitable screws to the piston 25. The flange 35 has apertures 36therein. The piston 34 has fixed therein an inner tubular member 3?terminating towards the piston 25 at a desired distance therefrom in anotched seating Further, the piston 3d at its front has a reducedstepped aperture, the upper portion 35 forming a seating for a ball (-0constituting a valve coming at the upper end of a projecting rod Msecured conoentricaliy in the enlarged portion 2'5 of the piston rod.

The recess 28 in the piston 25 open to the front of the piston 25through an annuiar passageway The whole arrangement is such that in theposition shown in Fig. 1 communication exists between the two sides ofthe piston That is to say, from the lower side the. oil is free to passthrough the aperture 33, the recess 29, the passageway 42 and theapertures 36 to the front of the piston.

When, however, the surfaces 3! and 32 are in contact (Fig. 2), then thispasageway is closed and even before the surfaces SH and 32 come intocontact any passageway through the apertures 33 is closed.

In this position, however, the ball 45 is either closely adjacent or incontact with the notched seating 38. This does not prevent pressureliquid passing through the member til and the notches, to act upon theupper surface of the piston 25.

The complete action readily will be appreciated; When the pressure fluidis permitted to pass to the tool, by valve control from an intensifieror the like through the hollow piston 34, the parts are in the positionshown in Fig. 1 and consequently the said fluid is precluded from actingupon the surface of the piston 25 as it cannot pass the ball valve Gil.Consequently it acts upon the subsidary piston 3:3 by exerting pressureon the tubular end thereof and upon the surface of the ball it. This issufficient to perform the approach portion of the stroke dur ing whichperiod oil with which the system is filled readily passes from the lowerside to the upperside of the piston 25 and also from the lower portionof the cylinder 3 (through the passageways 23) to the reservoir 2i.

When, however, the die it encounters its major resistance, then bycontinued action through the piston 34 and the piston 25, the sleeve 25slides over the enlarged portion 2'! and by its portion of smallerdiameter 28, over the piston rod 8.

The result is, the surfaces 3! and 32 are brought together, closing thepassage through the piston 25 for the oil and the ball valve E2 isremoved from its seat 39. As a consequence, the oil coming from theintensifier passes through the hollow member 3'! and the notched seating38 to and through the apertures 38 in order to act upon the uppersurface of the piston 25, and thus the pressure fluid exerts its effectthrough the large area of the said piston, to accomplish the purpose ofthe tool, such for example as riveting.

The return stroke is effected by a compression spring $3 on the underside of the piston 25, which surrounds the sleeve 26 and rod 9 andduring this return stroke the requisite amount of oil which comes abovethe piston 25 is returned to the intensifier. Further, when the pressureconditions are satisfied during the return stroke the spring 3!] againseparates the surfaces 3| and 32 to bring the parts into the positionshown in Fig. 1.

As will be appreciated, the air-filled cushion I8 automaticallycompensates for the varied volume of comparatively incompressible fluidsupplied to the space 2| duringthe action of the tool.

The upper portion of Fig. 2 indicates a variation of the structureforthe air-filled cushion and. shows two air-filled hollow ring 44,although only one such ring could be employed, or more than two, 'or insome cases such rings'could b replaced by hollow balls, or otherwise. I

Such a construction, however, modifies the arrangement for securing theclamping plate I! into position and in the construction shown in Fig. 2this plate I! takes the form of a stepped plate having additionalpacking members cooperating with its outer and inner contacts with thestructure.

In some cases the air-filled cushion on the interior of the press can bereplaced by a freely sliding piston arrangement with or without a returnspring, and further where required the reservoir for the fluid could bein a separate chamber fixed to the tool, for example at one'sidethereof, or separate therefrom.

Whatever form may be adopted, it willbe understood that as the Volume ofthe portion of the power cylinder behind the power piston decreases,pressure liquid therefrom automatically passes to the chamber orreservoir, the variation in volume of which is permitted by theair-filled cushion, spring-pressed piston, or otherwise.

It will be realised that the mechanism for operating the automatic valvemeans may be made in many other manners. For example, the power pistoncould be fixed to its piston rod or ram and spring means could beincluded between the end of the subsidiary piston and the power pistonwhich, for the approach portion of .the stroke would transmit thepressure from the subsidiary piston to the power piston but which wouldbe compressed for the working portion of the stroke, during whichcompression the valve means provided would be opened to give free.passage of the pressure liquid from the subsidiary cylinder to the powercylinder, to operate upon the working face of the power piston.

The invention is not limited to the precise forms or details ofconstruction described, as these may be varied to suit particularrequire- 1 ments. 7 r

What I claim and desire to secure by Letters Patent of the United Statesof America is:

1. In a machine of the character described, the combination of acylinder, a power piston in the cylinder, a tubular auxiliary pistonfixedly connected with the power piston, a closure for the andresponsive to impact of said means on a tubular piston, a' conduit foradmitting pressure cylinder, a tubular auxiliary piston fixedlyconnected with the power piston, a closure for the tubular piston, andmeans movable relatively to movement resisting element for opening theclosure and admitting pressure fluid through the 'tubular auxiliarypiston to the power piston.

4. In a machine of the character described, the combination of acylinder, 2. power piston in the cylinder, a tubular auxiliarypistonfixedly connected with the power piston, a closure for the tubularpiston, a tool supported by'the power piston movable relatively thereto,and means responsiveto impact of said tool on a movement resistingelement for opening said closure andadmitting the pressure fluid throughthe tubular auxiliary piston to the power piston.

5. In a machine of the character described, the combination of acylinder, a power pistonin the cylinder, a tubular auxiliary pistonfixedly connected with the power piston, a closure for the tubularpiston, a conduit for admitting pressure fluid against said closure toimpart movement to both of said pistons, and means supported by thepower piston and movable relatively to the same and responsive to impactof said means on a movement resisting element for opening said closureand admitting the pressure fluid through the tubular auxiliary piston tothe power piston, said power piston, auxiliary piston, closure andimpact responsive means forming a self-con tained structure as suchinsertible into and removable from thecylinder.

6. In a machine of the character described, the combination of acylinder containing pressure fluid, a power piston in the cylinderyatubular auxiliary piston fixedly connected with the power piston, aclosure for the tubular auxiliarypiston, a conduit for admittingpressure fluid against said closure to impart movement to both of saidpistons, and means on the power piston independent of the pressure fluidand responsive to impact on a movement resisting element for openingtheclosure and admitting the pressure fluid through the tubular auxiliarypiston to one side of the power piston, the power piston having apassage therethrough controllable by the-impact responsive means for theflow of the pressure fluid through said piston from the opposite side ofthe piston. '7. In a machine of the character described, the combinationof a cylinder containing pressure fluid, a power piston movable in thecylindena tubular auxiliary piston fixedly connected to the powerpiston, a closure for said tubular auxiliary piston, a conduit foradmitting pressure fluid to said cylinder, the closure being adapted toob struct the flow of pressure fluid from said conduit into thecylinder, a toolsupported by the power piston movable relativelythereto, and means responsive to impact of said tool on a movementresisting element for opening the closure and admitting the pressurefluid through said tubular auxiliary piston to one side of said powerpiston,

,the power piston and auxiliary piston having communicating passagestherethrough which are controlled by said means to establishcommunication b tween o h s es f the ow r p ston an auxiliary pistonconnected thereto,

, 3. In a machine of the character described, the combination of acylinder, a power piston mo able in the cylinder, a tubularauxiliarypiston fixedly connected with the power piston, a closure forthe tubular piston, a conduit for admitting pressure fluid against saidclosure to impart movement to both of said pistons, a tool supported bythe power pistonmovabl relatively thereto and responsive to impact on amovement resisting element for opening the closure and admittingpressure fluid through the tubular auxiliary piston to the power piston,a passage through the power piston, said tool being adapted to obstructthe flow of fluid through said passage from one side of the piston tothe other during a portion of its movement relative to the piston.

9. In a machine of the character described, the combination of acylinder, a power piston movable in the cylinder, a tubular auxiliarypiston fixedly connected with the power piston, a closure for thetubular piston, a conduit for admitting pressure fluid against saidclosure to impart movement to both of said pistons, a tool support bythe power piston movable relatively thereto, a fluid passage through thepower piston, and means responsive to impact of said tool on a movementresisting element for obstructing said passage while permittingcontinued movement of said power piston relatively to said tool.

10. In a machine of the character described, the combination of acylinder, a power piston movable in said cylinder, a tubular auxiliarypiston fixedly connected with said power piston, a closure for saidtubular auxiliary piston, a conduit for admitting pressure fluid againstsaid closure to impart movement to both of said pistons, impactresponsive means for opening said closure and establishing communicationbetween said conduit and one side of the power'piston, thecylindercontaining pressure fluid on both sides of the power piston, areservoir for pressure fluid outside said cylinder, a compressibleelement within said reservoir, and means for conveyin pressure fluidforced by movement of the power piston in the cylinder from the latterinto the reservoir against said compressible element.

11. In a machine of the character described, the combination of acyiinder containing fluid, a power piston movable in said cylinder, atool supported by said power piston and movable relatively thereto uponimpacting a movement resisting element, means for admitting pressurefluid into the cylinder upon encounter of the impact responsive tool tothe movement resisting element, a reservoir, a compressible andexpansible volume compensating element within said reservoir, means forconducting fluid forced from said cylinder into said reservoir and forcompressing said compressible volume'compensating thereby, passages fordirecting the pressure fluid expelled from said cylinder by movement ofthe piston into said reservoir, and a compressible element located insaid reservoir and adapted to compensate by its volume reductioneffected by the incoming fluid, for the increase in fluid volume in saidreservoir.

13. In a machine of the character described, the combination of acylinder, a power piston movable in said cylinder, an auxiliary tubular,piston fixedly connected with said cylinder in axial alinementtherewith, an impact responsive tool supported by said power piston andmovable relatively thereto, a conduit for admitting pressure fluid tothe cylinder, a valve for said auxiliary tubular piston supported bysaid impact responsive tool, and resilient means interposed between saidpower piston and said impact responsive tool for normally maintainingthe latter in predetermined relation to the power piston and for retainng the valve in closing position with respect to said cylinder.

lfl. In a machine of the character described, the combination of acylinder, a power piston movable in the cylinder, an auxiliary tubularpiston fixedly connected with the power piston, a conduit for admittingpressure fluid to said cylinder, said tubular auxiliary piston beingguided in said conduit, a valve normally obstructing flow of pressurefluid through said tubular auxliary piston, an impact responsive toolslidably carried by the power piston and supporting said valve, whereby,upon impact of said tool, said valve is raised from obstructingposition, and a spring interposed between said power piston and saidtool for normally retaining said tool in preetermined relation to saidpower piston.

15. In a machine of the character described, the combination of acylinder, a power piston movable in said cylinder, a conduit means foradmitting pressure fluid to said cylinder, a tubular auxiliary pistonfixedly connected to said power piston and movable in said conduitmeans, an impact responsive tool, an apertured sleeve on the powerpiston slidably supporting said irnpact responsive tool, a valve in saidauxiliary piston normally obstructing the flow of pressure fluid intothe cylinder, the tool supporting sleeve having apertures thereincommunicating with passages extending through the piston and said impactresponsive tool being adapted upon encounter of a movement resistingelement, to open the valve and obstruct the apertures through saidsleeve, and subsequently to close the passage through said piston.

16. In a machine of the character described, the combination, as setforth in claim 11, in which the compressible and expansible volumecompensating element within the reservoir is formed by a hollow, airfilled resilient member.

' 17. In, a machine of the character described, the combination, as setforth in claim 11, in which the compressible and expansible volumecompensating element within the reservoir is formed by a hollow annularmember filled with air.

18. In a machine of the character described, the combination, as setforth in claim 11, in which the compressible, expansiblevolumecompensating element within the reservoir is formed by an annular troughmember of V-shaped crosssection and made of resilient material.

ROBERT ALEXANDER CUTI-IBERT.

